Data Extracts From Another SQL Database

We have an engineering software which was not designed for SQL use. Basically what they have are a bunch of tables, and in those table values are comma delimted lists. They then created views off these crappy tables and created a "key" in the view.. I'm not sure you already guessed that this sucks for writing reports and things of that nature, so, I decided to create my own database and create extracts.

I know how to get new data into the tables which I'll outline one below, but the part I'm not sure of how to do is how to see if a value is changed. They don't have timestamps tracking a update otherwise I'd just check against that and I'd rather prefer so just update data that needs to be versus doing a complete wipe of the data. Some of the data (such as sales orders) the employees requested to be extracted live however I was able to negotiate with them down to every 15 minutes.

Here's what my table looks like for customers..  CustomerId int NOT NULL,
CustomerNumber nvarchar(16),
CustomerName nvarchar(100),
BAddress1 nvarchar(100),
BAddress2 nvarchar(100),
BCity nvarchar(50),
BState nvarchar(10),
BZip nvarchar(15),
SAddress1 nvarchar(100),
SAddress2 nvarchar(100),
SCity nvarchar(50),
SState nvarchar(10),
SZip nvarchar(15),
Phone nvarchar(30),
Fax nvarchar(30)


And this is how i'm inserting new data.INSERT INTO Intranet.dbo.FS_Customer
SELECT
c.CustomerKey,
c.CustomerID,
c.CustomerName,
c.BillToAddress1,
c.BillToAddress2,
c.BillToCity,
c.BillToState,
c.BillToZip,
c.CustomerAddress1,
c.CustomerAddress2,
c.CustomerCity,
c.CustomerState,
c.CustomerZip,
c.CustomerContactPhone,
c.CustomerContactFax
FROM
FSDBKL.dbo.FS_Customer AS c
WHERE c.CustomerKey NOT IN (SELECT cu.CustomerId FROM intranet.dbo.FS_Customer AS cu)

 

FSDBKL.dbo.FS_Customer is the old table, and intranet.dbo.FS_Customer is the new one I created.

If I have to I can update each record but right now the customers table alone has 9,000 records and I think doing a update on each record will be time consuming.